Amblyopia is usually considered to be a deficit in spatial vision. But
there is evidence that amblyopes may also suffer specific deficits in
motion sensitivity as opposed to losses that can be explained by the known
deficits in spatial vision. We measured sensitivity to visual motion in
random dot displays for strabismic and anisometropic amblyopic monkeys. We
used a wide range of spatial and temporal offsets and compared the
performance of the fellow and amblyopic eye for each monkey. The amblyopes
were severely impaired at detecting motion at fine spatial and long
temporal offsets, corresponding to fine spatial scale and slow speeds.
This impairment was also evident for the untreated fellow eyes of
strabismic but not anisometropic amblyopes. Motion sensitivity functions
for amblyopic eyes were shifted toward large spatial scales for amblyopic
compared to fellow eyes, to a degree that was correlated with the shift in
scale of the spatial contrast sensitivity function. Amblyopic losses in
motion sensitivity, however, were not correlated with losses in spatial
contrast sensitivity. This, combined with the specific impairment for
detecting long temporal offsets, reveals a deficit in spatiotemporal
integration in amblyopia which cannot be explained by the lower spatial
resolution of amblyopic vision.